Tank



Dec. 17, 1935. H. BABcocK 2,024,327

TANK v Filed Nov. 14, 1932 2 ets-Sheet 2 v WIIIIIIIIILYI enema Dec. 11,1935 y UNITED STATES PATENT OFFICE` y TANK Harry L'. Babcock, EastChicago, Ind., assignor to i Graver Tank & Manufacturing Co., East Chi.cago, Ind., a corporation of Illinois Application November 14, 1932,Serial No. 642,485

'z Claims.' -(Ci. 22o-26) This invention relates to storage. tanks, suchas are used for storing oil or gasoline, and has been illustrated asembodied in a oating roof type of tank. In the storage of lgasoline andother volatile and combustible material, various problems arise. A fixedroof is unsatisfactory when the -tank is only partially full', because alarge vapor space is left above the gasoline which, of course, 'isunsafe on account of the danger of explosion, and because it must becompletely -self-sustaining. -It is, therefore, preferred to use afloating roof which, by its nature, eliminates the major portion of thegas space by resting on the oil. l5 With floating roofs, however,- thereare the problems of sealing the edges so far as possible withoutmaterially affecting the movement of the roof, and withoutpermitting theformation of a gas pocket of any considerable size in connectior'i withthe seal, and of minimizing Athe 'I surface exposed forA evaporation.According to the present. invention, these problems are solved byconstructing a floating roof similar in many respectsto other floatingroofs, but provided withl a series of oats around and under theperipheral portion arranged to seal against the floating roof and thesides of the tank under the influence of their buoyancy, and soconstructed as to minimize the presence of vapor pockets. Btl-'In such aroof there would of course be the problem of inserting and replacing thefloats, and this has been met by providing hatches of a special form.Such a roof involves also the problem of providing a seal to decreaseevaporation and watersheds so that water striking on i the iioats willso far as possible drain onto the roof rather than into the tank. Thisproblem has been met by providing special sealing members which overlapthe sides of the floating roof, and each other, and which are soattached to the oats as to be readily accessible.

With these and various other objects in view, the invention may consistof certain novel features of construction and operation, as will be morefully described and particularly pointed out in the specification,drawings and claims appended hereto.

In the drawings, which illustrate an embodiment of the device, andwherein like reference characters are used to designate like parts,

' Figure 1 is a plan view of a tank;

Figure 2 is a vertical cross-sectional view of the construction ofFigure 1 built in accordance with this invention;

Figure 3 is a detail sectional view showing particularly theconstruction of the float and its relation to the roof, and is across-section taken through the line 3-3 of Figure 4;

Figure 4 is a plan view of Figure 3;-

Figure 5 is across section through the-line 5 5 5 of Figure 6, andillustrates primarily the construction of the hatchway; and

Figure 6 is a plan view of the structure shown in Figure 5.

Although my invention may take many forms, l0 only one has been chosenfor illustration. In this form the central portion of the roofillustrated in Figure 1 is commonplace and has been shown simply for thepurpose of illustration. The roof may comprise the deck bottom I0 suitl5ably reinforced by beams I2 which may extend radially and alsocircumferentially of the deck. Preferably one of these beams or girdersextends around the periphery of the deck bottom, as at Ill. Suitablesuper-structure I6 may be pro- 20 vided for bracing the deck andmaintaining it in the shape desired, so that Water will properly iiowfrom the periphery to the center or to such other drainage point as maybe provided, from which it may be drained in any well known man- 25 ner.Welded or otherwise secured around the periphery of the deck bottom l0are the deck sides 2li which extend upwardly at a suitable angle, aswill be described hereinafter. Beneath the deck side 20 are the floats22 which press against 30 the deck sides 20 and against the tank wall24. At any convenient number vof locations there may be providedsuitable hatchways 26 for permitting the removal of the oats. Suitablemeans for draining and filling the tank are of 35 course also provided,though for the sake of simplicity they have not been shown. Legs 28 havebeen indicated for supporting the vroof as the oil is drained out fromthe tank, to prevent injury of the roof or the parts under it. Fig- 40ure 2 illustrates the same structure in about the same scale, andtherefore it gives a more clear arrangement of the various partsmentioned. It may be noted at this point that guides are usuallyprovided for keeping the main portion 45 of the roof centered withrespect to the tank,

but these have been omitted for. the sake of clarity.

Most of the novel details are shown best in Figures 3 to 6. In Figure 3are shown the details 50 of a float and its seal. The float is providedwith a curved outer surface 32 which contacts the side of the tank andis curved enough to prevent the float from catching on outstandingrivets or joints between plates or other obstructions. The 55 2 outer my'be provided with' a' contact plat! Il which preferably extendsthlollhlit thcsurface of the outer end 22, and ifdeaired may be made ofsome non-corrosive metal, or'may be coated or covered with anon-corrosive. metal, such as brass. The top 36 of the float is formedat an angle corresponding to the'angle of the deck side 2l, and ispreferably of thesame shape, so as to contact therewith throughout theoverlapping surfaces. At this positon there is pref-- erably provided acontact plato '28. coextensive.

with the top Il and made of' copper, brass, or

1 other non-corrosive metal to avoid all danger -due to rust formingbetween the top l! andthe deck side 2l, and preventing their propersliding action. Ihis plate is preferably welded or otherwisc securedtothe top 26. The float itself may be made of any desired metal.

'me angie of the deck side zo is quite important, for if it is toosteep, the floats 22 will not be properly thrust inwardly by downwardmove-V ment of the roof when the oat hits some ob-l tory. and experimentunder particular conditions may show that angles which are quitedifferent would be satisfactory so long as the inclination is at leastas great as the critical angle for sliding under the influence ofbuoyancy alone.

- The critical angle means the angle below which the pontoons will notbe slid by their buoyancy under the particular conditions of any giventank; the particular conditions including, for example, the qualities ofthe metal surfaces. In the 'claims the term effective vinclination ofthe sliding surfaces has been used to cover the possibility that theremay-be only one inclined surface (if it was nevertheless effective as aninclined surface) and to exclude inclined surfaces which did notfunction as such. The deck side 2l is preferably made up of severalstrips buttwelded together topresent a smooth under surface. The jointsbetween these strips may be overlaid with extra strips of metal for thepurpose of reinforcement and to insure perfect drainage if desired.

-The side plate 24 of the floats extends upwardly above the float toprovide a flange 46 thereabove. To each of these flanges is secured,preferably by.bolts 42. a seal plate 44. This seal plate is arranged to.extend over the deck side 20 and is preferably provided with a groove 46into which maybe inserted packing 48 to render the seal morewater-tight. Both the packing 46 and the flanges forming the groove 46may be omitted whenever necessary, as at the points where occur thejoints in the deck side 2li. In order to protect the joints between thefloats and the seals-from leakage as much as possible, an overlap andseal strip 6l may be provided on each seal plate 44 preferably bywelding. Such overlap seal strip extends across the :um s ma c. in whenn deaf-mm the man proper. As illustrated'therein, this hatch is lc-Icured to the deck sidell by suitable screws Il which-may screw into afacing plate It welded toth'edeckside 2l. Agaskotofcoursemaybc 5 iprovided if desired. In order to prevent nooding of the roof when thehatch is opened. or in the event it should leak. the hatchwa'y--isformed f with a water-tight housing Il around the hatch I4. the sidesand back-of which may be welded 10 to each other and to the de:k. Forthe sake of simplicity, the seal plates have vbeen omitted from Figures5 and 6, but it should be understood that they would normally-be used,and would be pro- 'float may be slid to the position of the hatchway 25and removed.

'I'he operation of the structure hardly needs explanation. As the deckisv raised or lowered by the change in the level of the oil, the floats22 are likewise raised and lowered. In any given position the float 22is pressed by its buoyancy against the deck side 20 and by its co-actionwith' this deck side is pressed outwardly against the tank wall 24. Whenthe deck is raised or lowered, if the float should strike a rivet orother projection it would slide the float inwardly along the deck side20. As soon as the projection is passed, the buoyancy of the float andits reaction on deck 'side 20 thrusts the float outwardly and upwardlyinto its normal sealing position. With the structure shown, it is 40evident that both the surface exposed for evaporation and the volume ofgas pockets has been reduced to a minimum, if the weight of the deck issuch that it would sinksutliciently deeply to submerge the corner 64.The only surface exposed would be that between the floats 22 and that onthe outside of the floats 22. These oats are located as close togetheras possible, so that the surface exposed between them would be extremelysmall. Likewise the curvature of the outside of the floats is such thatexcept when a float is pressed in by a. rivet or the like, the surfaceof the oil exposed on the outside of the oat would also be quite small.Inasmuch as the air contacting with the surface in both places wouldnormally be stagnant, the evaporation would be almost negligible. Incommercial productions, it might of course often occur that the corner64 would not be submerged, and so the exposed surface would be slightlygreater but it would nevertheless be 00 considerably less than in anyformer structure having the other advantages of this roof.'

It is to be understood that many other embodiments of the invention,including some in improved form, will be apparent, and in the course 65of time more will be devised by those skilled in the art. It is notdesired that this invention be limited to the details described, for itsscope includes all such forms or improvements as come within the spiritof the following claims, construed as broadly as the prior art willpermit.

What ls claimed is:

l. 'I'he combination of a tank for the storage of oil and the like, anda floating roof therein; said floating roof including a deck having anupwardly and outwardly extending peripheral portion which extends abovethe level of the oil, and a series of freely movable floats below saidperipheral portion arranged to form a seal between the same and the wallof-said tank: said peripheral portion having spaced hatchways formedtherein for permitting the removal of said floats.

A 2. The combination of a tank for the storage of oil and the like, anda floating roof therein; said floating roof including a deck having anupwardly and outwardly extending peripheral portion which extends abovethe level of the oil, and a series of oats below said peripheral portionarranged to form a seal between the same and the wall of said tank; saidperipheral portion having hatchways formed therein for permitting theremoval of said oats; said hatchways including upwardly extending wallshaving water-tight joints with said deck and arranged to prevent thepassage of liquid from said hatchway onto the main portion of said deck.

3. The combination of a tank for the storage of oil or the like; avertically movable roof in said tank including a deck having aperipheral portion smaller than said tank: a series of floats beneathsaid peripheral portion pressing upwardly thereon, one of the contactingsurfaces between each said iloat and said peripheral portion being soinclined as to react to said buoyancy and press said iloat outwardlyagainst the wall ci' said tank; and a watershed extending from a pointadjacent an upper and outer portion of each said iloats downwardly andinwardly and over said peripheral portion.

4. 'I'he combination of a tank for the storage of oil or the like; avertically movable roof in said tank including a deck having aperipheral portion smaller than said tank; a series of oats beneath saidperipheral portion pressing upwardly thereon, one of the contactingsurfaces between each said iloat and said peripheral portion being soinclined as to react to said buoyancy and press said iioatoutwardlyagainst the wall of said tank;

and a watershed secured to an upper and outer portion of each said oatsand extending down.

wardly and inwardly and over said peripheral portion.

5. The combination of a tank for the storage of oil or the like; avertically movable roof 'in said tank including a de ck having aperipheralportion smaller than said tank; a series of iioats b eneathsaid peripheral portion pressing upwardly thereon, one of the contactingsurfaces between each said iloat and said peripheral portion being soinclined as to react to said buoyancy and press g said iloat outwardlyagainst the wall of' said tank; and a watershed secured to an upper andouter portion of each said float and extending downwardly and inwardlyand over said peripheral portion, said watershed carrying a flexible 10sealing strip in contact with said peripheral portion.

6. The combination of a tank for the storage of oil or the like; avertically movable roof in'said tank including a deck having aperipheral portion 15 slightly smaller than said tank; and a series offloats beneath said peripheral portion pressing upwardly thereon andhaving a sliding engagement therewith and with the wall of the tank; thewall engaging surface of each said iioat being 90 so cam-shaped thatwhen said float is raised or lowered against projections it will bepressed inwardly, the contacting surfaces between said floats and saidperipheral portion being inclined at such angle that the buoyancy of thefloats alone will be effective to cause them to slide outwardly and theinward thrust of said projections will be eective when the roof islowered to slide said floats inwardly, said inclination beingapproximately thirty-live degrees.

7. 'I'he combination oi',I a tank for the storage of oil or the like; avertically movable roof in said tank including a deck having aperipheral portion slightly smaller than said tank; and a series offloats beneath said peripheral portion pressing upwardly thereon andhaving a sliding engagement therewith and with the wall of the tank; thewall engaging slu'face of each said iloat being so cam-shaped that-'whensaid iloat is raised or lowered against projections it will be pressedin- ,u wardly. the contacting surfaces between said floats and saidperipheral portion being inclined at such angle that the buoyancy of thefloats alone will beeifective to cause them to slide outwardly and theinward thrust of said projections will be e'ective when the roof islowered to slide said iloats inwardly. said inclination being thirtyiivedegre with substantial exactitude.

L. BABCOCK.

